Abstract
The compound KF·4HF, prepared by the addition of anhydrous hydrofluoric acid to potassium fluoride, is shown, on the basis of an X-ray structure determination, to be potassium tetrahydrogen pentafluoride, K[H4F5]. The material crystallizes with four formula units in the tetragonal space group C4h6-I41 a in a cell of dimensions a = 6.384(3), c = 13.227(7) Å. The conventional R factor for the 221 intensities observed above background is 6.2%. The structure is of the scheelite type, with the potassium and the central fluorine atoms residing at special positions of symmetry 4, and the other fluorine atoms hydrogen bonded to the central fluorine atom at an FH···F distance of 2.453(2) Å. The resultant H4F5- ion, which is crystallographically required to possess 4 symmetry, exhibits a slight but significant distortion from tetrahedral geometry. The FH···F bond is approximately linear and is unsymmetric with the hydrogen closer to the peripheral fluorine. The fluorine atoms in the immediate environment of the potassium atom form a dodecahedron with triangular faces.
Original language | English (US) |
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Pages (from-to) | 386-393 |
Number of pages | 8 |
Journal | Journal of Solid State Chemistry |
Volume | 1 |
Issue number | 3-4 |
DOIs | |
State | Published - Apr 1970 |
Funding
A comparisono f the fluorine-fluorineh ydrogen- bondedd istancew ith thosei n otherH F compounds is given in Table VI. One may rationalizet he ob-Acknowledgments servedt rendb y assumingth ata st hee lectronso f the The preparationo f the crystal was carried out in Dr. H. H. fluorine atomsb ecomele ssa vailablef or hydrogen-Hyman’s laboratory at Argonne National Laboratory, bonding, then the F-H-*-F bond becomeslo nger. operated for the U.S. Atomic Energy Commission. It is a This is consistentw ith either an increasei n the pleasuret o acknowledget he cooperationa nd hospitality that coordinationn umbero r especiallyw ith a decrease Dr. Hyman provided. This work was supportedb y Advanced in formal negativec hargeo n the fluorine atoms. Research Projects Agency of the Department of Defense Despitet he fact that the presents tructurew as through the Northwestern University Materials Research derivedf rom X-ray data that were not collected Center. BAC acknowledgesa fellowship from the National undert hem ostd esirablec onditionst, herea res everal DefenseE ducation Act. lines of evidenceth at suggestth at thed etermination JAI wishes to acknowledget he deep personal loss engen- is a reliableo ne. Not only is the final value of R, deredb y the untimelyd eatho f A. D. Wadsley. of 0.062 fairly low but the atomic mean-square amplitudeso f vibration( TableV II) seemre asonable References enougha s do the directionso f thermalm otion,a nd these thermal parameterss hould be particularly sensitivet o residuale rrorsi n the data.T he periph- eral fluorineF (2) is the only atoms howinga ppreci- ablea nisotropicv ibrationa nd, as can be seenin the figures,t he axis of largestr oot-mean-squaraem pli- tude is roughly perpendiculart o the plane formed by its nearestF (1) and K neighbors.I n addition,
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry